Hi, I just got in trouble (again.)

In exclamations and imperatives, is the reason for the wierd agreement situation that they are considered subjunctive, or that the verb (in the following sentence) is actually "hear," and "bark" is not really a verb?

Hear the dog bark! Hear the dogs bark!
Bark is infinitive.
Thanks, Mr. M. I had misplaced my thinking cap.

- A.